Auto merge of #11867 - y21:implied_bounds_in_impls_complexity, r=Jarcho

Move `implied_bounds_in_impls` back to complexity

This lint was originally in the complexity category when I PR'd it. It was then moved to nursery by me due to a number of issues (a false positive, an invalid suggestion and an ICE), but that was probably an overreaction and all of the issues were fixed quickly after.
This is a useful lint imo and there hasn't been any issues with it in a few months, so I say we should give it another try and move it back to complexity.

I did a lintcheck run on the top 400 crates and all of them are legitimate, with 18 warnings. Most of them are from anstyle having a `impl Display + Copy + Clone` return type, or the bitvec crate with a return type like `impl Iterator + DoubleEndedIterator`.

changelog: Move [`implied_bounds_in_impls`] to `complexity` (Now warn-by-default)
[#11867](#11867)

clippy_lints/src/implied_bounds_in_impls.rs

@@ -45,7 +45,7 @@ declare_clippy_lint! {
     /// ```
     #[clippy::version = "1.74.0"]
     pub IMPLIED_BOUNDS_IN_IMPLS,
-    nursery,
+    complexity,
     "specifying bounds that are implied by other bounds in `impl Trait` type"
 }
 declare_lint_pass!(ImpliedBoundsInImpls => [IMPLIED_BOUNDS_IN_IMPLS]);